Week 6 Labs

What spontaneously generates electrical activity of the heart?

Sinoatrial (SA) node

What is known as the pacemaker of the heart?

Sinoatrial (SA) node

What stimulates the myocardium of the atria to contract?

electrical impulse through right & left atria

What functions as a critical delay in the conduction system, preventing atria & ventricles form contracting at the same time?

atrioventricular (AV) node

What is the distal portion of the atrioventricular (AV) node called?

AV bundle or bundle of His

What stimulates individual groups of ventricular myocardial cells to contract?

purkinji fibers

What causes the heart to contract?

electrical current passing through the heart → cardiac tissue is excited

What happens to muscles cells after they contract?

they relax until the next electrical current passes → repeats

What interprets electrical activity (depolarization and repolarization) of the heart one ra period of time?

electrocardiogram (ECG)

What are attached to the skin during an electrocardiogram?

electrodes

Where are the electrodes usually placed on the body during an electrocardiogram?

left arm (LA), right arm (RA), left leg (LL)

What is formed when electrodes are placed on the left arm, right arm, and left leg?

Einthoven’s triangle

What is the output of each electrode during an electrocardiogram known as?

a lead

What is the area between two waves called?

segment

What is a straight line and one or more waves known as?

Interval

What is more than one wave appearing succession of one another known as?

complex

Which component of an ECG is the depolarization of atrial fibers at the SA node?

P-wave

Which component of an ECG is the time from start of depolarization of atrial fibers to the start of depolarization of ventricles?

P-R interval

Which component of an ECG is the time for cardiac impulse to pass through the AV node?

P-Q segment

Which component of an ECG is depolarization of ventricular fibers?

QRS complex

Which component of an ECG is the time for ventricles to contract

S-T segment

Which component of an ECG is the time from ventricular depolarization to the end of ventricular repolarization?

Q-T interval

Which component of an ECG is the repolarization of ventricular fibers?

T-wave

Which component of an ECG is the time of relaxation & filling of the heart between beats?

T-P segment

How to calculate heart rate?

divide 60 by the R-R interval

If the heart rate increases, what changes would you expect to see int he ECG?

the R-R interval decreases

How are interval and segment different?

interval measures at least one wave & one flat area, while segment includes only a flat area

What happens to the heart rate as the R-R interval decreases?

the heart rate increases

Which waveform has the second largest change in duration after the R-R interval?

T-P segment

After 5 minutes of exercise in the lab, did the heart rate increase or decrease? by how much”

heart rate increased by 60 (it doubled)

Besides the heart rate, did the components of an ECG increase or decrease after 5 minutes of exercise?

decrease

What causes changes in pressure between the heart chamber, causing the valves to open and close?

contraction (systole) and relaxation (diastole)

What is the main purpose of heart valves?

make sue blood only flows in one direction

What are the 2 sounds the heartbeat consists of?

“lubb - dupp”

What are the 2 atrioventricular (AV) valves?

right AV valve

left AV valve

What is another name for the right AV valve?

tricuspid valve

What is another name for the left AV valve?

bicuspid/mitral valve

What creates the “lubb” sound and when?

closing of 2 AV valves at start of ventricular systole

What are the 2 semilunar valves?

pulmonary semilunar valve

aortic semilunar valve

Where is the pulmonary semilunar valve located?

between right ventricle and pulmonary trunk

Where is the aortic semilunar valve located?

left ventricle and aorta

What makes the “dupp” sound and when?

closing of 2 semilunar valves at start of ventricular diastole

What is the most anterior point of the heart that is located int he fifth left intercostal space?

Apex

What is the most posterior and superior aspect of the heart?

Base

What is located at the manubriosternal joint and is important for identifying intercostal space?

sternal angle

What is the first heart sound and what creates it?

lubb

closure of AV valves

During which phase of cardiac cycle is the first sound heard?

ventricular systole

What is the second heart sound called and what creates it?

dupp

semilunar valves

During which phase of the cardiac cycle is the second heart sound heard?

ventricular diastole

In the lab are patients 1, 2 and 3 normal or abnormal?

patient 1: normal

patient 2: abnormal

patient 3: normal

If you hear an abnormal sound in between the two normal heart sounds, during which phase of the cardiac cycle is the abnormal sound occurring?

ventricular systole

If you hear an abnormal second heart sound, which valve could be affected?

pulmonary semilunar valve & aortic semilunar valve

In a patient with normal heart sounds, what would you hear int he fifth left intercostal space at the mid-clavicular line?

loud & strong “lubb” sound

Which valve is heard from the 2nd intercostal space on the right side of the sternum?

aortic semilunar valve

Which valve is heard from 2nd intercostal space on the left side of the sternum?

pulmonary seminar valve

Which valve is heard at the 4th or 5th intercostal space to the left of the sternum?

right AV (tricuspid) valve

Which valve is heard form the 5th intercostal space on left side of mid-clavicular line?

left AV (bicuspid/mitral) valve